In the field of accelerometers, it is known to form a small compact accelerometer by etching the relevant parts out of silicon. U.S. Pat. No. 4,574,327 illustrates one version of such a transducer in which a proof mass having a textured surface containing many grooves and apertures extending through the proof mass has its surface tailored in order to achieve the desired frequency response by using the squeeze-film damping phenomenon. In that apparatus, response is hindered by the fact that the surface of the proof mass is corrugated and is not uniform so that the capacitance is much less than it would be if the surface were smooth. Further, the removal of a substantial portion of mass limits the amount of mass available and thereby decreases the sensitivity of the accelerometer.
Other forms of micro-accelerometers employ cantilever proof masses that introduce an asymmetry that can give an undesirable cross-axis sensitivity. The preceding '327 patent avoids that asymmetric effect by showing a flexible hinge all around the proof mass so that the response is directed preferentially to an axis perpendicular to the plane of the proof mass.
The problems evidenced by such prior art devices are the difficulty of tailoring the parameters of the device to accommodate different ranges of acceleration to be measured and the different ranges of frequency response of the device. In a typical design, the mechanical, damping and electrical parameters are interrelated so that changing one parameter will have an adverse affect on others.